A250678 - OEIS

%I #4 Nov 26 2014 18:21:47

%S 520,5154,42422,329226,2406972,16949262,115965426,777137322,

%T 5127532140,33440743748,216192271674,1388450185042,8872367832376,

%U 56479411574776,358489567889570,2270374738759036,14354245060678584,90635411405776404

%N Number of (2+1)X(n+1) 0..3 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction

%C Row 2 of A250676

%H R. H. Hardin, <a href="/A250678/b250678.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 19*a(n-1) -115*a(n-2) +64*a(n-3) +1793*a(n-4) -4621*a(n-5) -9264*a(n-6) +41507*a(n-7) +14863*a(n-8) -173352*a(n-9) +31915*a(n-10) +399081*a(n-11) -166415*a(n-12) -530154*a(n-13) +278712*a(n-14) +400256*a(n-15) -230016*a(n-16) -156992*a(n-17) +92352*a(n-18) +24192*a(n-19) -13824*a(n-20)

%e Some solutions for n=3

%e ..2..2..1..0....3..1..0..0....3..1..1..1....3..0..3..1....0..1..0..1

%e ..3..1..2..2....3..2..1..1....2..2..2..2....2..2..1..3....1..2..1..2

%e ..2..2..3..1....2..3..2..2....2..2..3..3....1..3..3..1....1..2..2..3

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 26 2014